Solve the Equation by Making an Appropriate Substitution $$2 x - 9 \sqrt { x } - 56 = 0$$

Multiple Choice

Solve the equation by making an appropriate substitution.
- $$2 x - 9 \sqrt { x } - 56 = 0$$

A) $\{ 8 \}$
B) $\{ 64 \}$
C) $\left\{ \frac { 49 } { 4 } , 64 \right\}$
D) $\left\{ \frac { 7 } { 2 } , 8 \right\}$